The document summarizes the stepwise interpretation of an ECG for a 78-year-old woman with a heart murmur. It finds sinus rhythm at 77 beats per minute with sinus arrhythmia and first-degree AV block. There is also evidence of left ventricular hypertrophy with ST-T abnormalities and no signs of myocardial infarction.

1. Stepwise interpretation of ECG ID 168 – LVH

2. ID 168 78 year old woman with a heart murmur

3. ID 168 78 year old woman with a heart murmur Can you see P waves?

4. ID 168 – Sinus rhythm, 77/min with sinus arrhythmia – First degree AV block Yes, there is sinus rhythm, 77/min. The P-P interval varies in keeping with sinus arrhythmia (a common normal finding) – Each P is followed by a QRS – The P-R is prolonged to 230 msec. (1 st degree AV block)

5. ID 168 - Sinus rhythm, 77/min with sinus arrhythmia – First degree AV block There are no signs of right or left atrial enlargement

6. ID 168 - Sinus rhythm, 77/min with sinus arrhythmia – First degree AV block Let’s now look at the QRS complexes: There is normal QRS axis (between 0 and 90 degrees

7. The QRS duration is normal : There is no right bundle branch block, left bundle branch block or non‐specific block ID 168 - Sinus rhythm, 77/min with sinus arrhythmia – First degree AV block

8. ID 168 - Sinus rhythm, 77/min with sinus arrhythmia – First degree AV block – Left ventricular hypertrophy with repolarization abnormality There are findings of left ventricular hypertrophy with ST-T abnormality (“strain pattern”)

9. ID 168 Sinus rhythm, 77/min with sinus arrhythmia – First degree AV block Left ventricular hypertrophy with repolarization abnormality There are no QRS changes of myocardial infarction

10. ID 168 Final diagnosis - Sinus rhythm, 77/min with sinus arrhythmia – First degree AV block Left ventricular hypertrophy with repolarization abnormality